This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A242209 #12 Nov 05 2015 08:41:03 %S A242209 38,339,579,1731,5739,8499,32259,133851,145779,163851,207579,222531, %T A242209 235779,260187,308019,323619,366819,469731,550491,644979,684699, %U A242209 743091,926427,1003539,1242939,1743531,1808259,1852107,1909059,2075091,2585571,4226979,5358291 %N A242209 Semiprimes sp = p^2 + q^2 + r^2 where p, q and r are consecutive primes. %C A242209 Subsequence of A133529. %C A242209 All the terms in the sequence, except a(1), are divisible by 3. %H A242209 K. D. Bajpai, <a href="/A242209/b242209.txt">Table of n, a(n) for n = 1..5100</a> %e A242209 a(1) = 38 = 2^2 + 3^2 + 5^2 = 2*19 is semiprime. %e A242209 a(2) = 339 = 7^2 + 11^2 + 13^2 = 3*113 is semiprime. %p A242209 with(numtheory): A242209:= proc()local k ; k:=(ithprime(x)^2+ithprime(x+1)^2+ithprime(x+2)^2); if bigomega(k)=2 then RETURN (k); fi;end: seq(A242209 (),x=1..500); %t A242209 Select[Total[#^2]&/@Partition[Prime[Range[300]],3,1],PrimeOmega[#]==2&] (* _Harvey P. Dale_, Nov 05 2015 *) %o A242209 (PARI) for(k=1, 500, sp=prime(k)^2+prime(k+1)^2+prime(k+2)^2; if(bigomega(sp)==2, print1(sp, ", "))) \\ _Colin Barker_, May 07 2014 %Y A242209 Cf. A001358, A133529, A216432. %K A242209 nonn %O A242209 1,1 %A A242209 _K. D. Bajpai_, May 07 2014